Valve obturator

ABSTRACT

An obturator prevents the tips or flaps of a duck-bill valve from self-adhering during storage or during sterilization procedures. The obturator holds the tips apart until the end-user is ready to use the valve. The duck-bill valve is used as an air outlet valve in blood reservoirs.

FIELD OF THE INVENTION

[0001] This invention relates to a blood reservoir for use in anextracorporeal blood circuit. In particular, this invention relates to ameans for preventing self-adhesion of a one-way air outlet valve in theblood reservoir.

BACKGROUND OF THE INVENTION

[0002] In cardiopulmonary bypass operations, a patient's circulatorysystem is linked to a heart-lung machine to permit the extracorporealcirculation of blood. In these surgical procedures, a bypass circuit iscreated where venous blood bypasses the heart and is reintroduced intoan artery. Also, cardiotomy blood is scavenged from the surgical site,combined with the venous blood, and reintroduced into the patient. Theextracorporeal bypass circuit performs numerous functions, includingremoving emboli and particulate matter entrained in the blood,regulating the carbon dioxide and oxygen content of the blood, andregulating the blood temperature.

[0003] In the past, venous blood was filtered and collected in a venousreservoir and the cardiotomy blood was filtered and collected in acardiotomy reservoir. Work in this art area has included efforts tosimplify and improve these systems, as, for example, providing combinedvenous and cardiotomy reservoir systems. Other work has been directed tosimplifying and improving the blood storage, filtration, and defoamingsystems for both venous and cardiotomy blood.

[0004] In some systems, a sealed venous reservoir is used. This allows avacuum to be pulled in the reservoir for the purpose of assisting theremoval of blood from the patient. However, using such sealed systemscreates a potential problem. During the surgical procedure, it ispossible to develop either over-or under-pressure situations within thesealed reservoir. Either situation can lead to undesirable consequencesfor the patient. Therefore, it is known to use safety valves which canregulate the pressure within the sealed reservoir so that it does notexceed acceptable positive and negative pressure limits.

[0005] Safety valves include unidirectional valves such as umbrellavalves and duck-bill valves. A unidirectional valve permits the escapeof air when there is a positive or negative air pressure within thereservoir. Umbrella valves typically are used to vent negative pressurein a reservoir. Duck-bill valves typically are used to vent positivepressure. This valve includes two tips or flaps and an integral basedefining a generally cylindrical opening. The tips or flaps butt againsteach other preventing the passage of air in or out of the reservoir,responding to positive pressure within the reservoir by spreading apart.Duck-bill valves in current use typically are comprised of siliconematerials which are engineered to respond to certain pressures, thusallowing fluid to flow through the valve at desired pressures.

[0006] We have discovered that the tips or flaps of duck-bill valvesused as air outlet valves in blood reservoirs can adhere together afterlong periods of time or after exposure to adverse environmentalconditions. Typically such valves comprise silicone. This self-adhesionis an extremely undesirable situation, as a non-functioning valve canproduce a build-up of pressure in a venous reservoir, resulting inreverse blood flow. Thus, a need exists to prevent the self-adhesion ofduck-bill valve tips when the duck bill valve is used as a safety valvein blood reservoirs.

SUMMARY OF THE INVENTION

[0007] We have invented a device, termed an “obturator”, which preventsthe tips or flaps of a duck-bill valve from self-adhering during storageor during sterilization procedures. The obturator holds the tips apartuntil the end-user is ready to use the valve. The duckbill valve is usedas an air outlet valve in blood reservoirs.

[0008] In one aspect, this invention is a method for preventingself-adhesion of the tips of a duck-bill valve during sterilization byproviding an obturator having a plunger element; and inserting theplunger element between the tips of the duck-bill valve prior tosterilization.

[0009] The plunger element may be comprised of polymeric materials.Preferably, the plunger element is joined to a cap for ease of insertionand removal. More preferably, the plunger element and the cap are formedor molded from a single piece of plastic.

[0010] In a second aspect, this invention is a sealed blood reservoircomprising a top, a bottom, and a continuous sidewall, the top andbottom connected to the sidewall to form a sealed housing; the sealedhousing defining an interior chamber; the housing having a blood inletand a blood outlet in flow communication with the interior chamber; aduckbill valve having two tips and an integral body in communicationwith the interior chamber; and an obturator comprising a plunger elementpositioned between and separating the tips of the duck-bill valve.

[0011] In a third aspect, this invention is a method of preventingpressurization of a sealed blood reservoir by providing a sealed bloodreservoir as described above, providing a duck-bill valve having twotips and an integral body in communication with the interior chamber ofthe reservoir; and inserting a plunger element between the tips of theduck-bill valve, wherein the plunger element prevents the tips of theduck-bill valve from self-adhering.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a perspective view of the obturator according to thepresent invention.

[0013]FIG. 2 is a perspective view of the obturator of this inventioninserted between the tips of a duck bill valve.

[0014]FIG. 3 is a cross-sectional view of a hard shell blood reservoirshowing the placement of the duck-bill valve and the obturator of thepresent invention.

[0015]FIG. 4 is a cross-sectional view of the obturator and valve shownin FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The obturator of this invention is useful with duck-bill valvesthat are used in closed or sealed blood reservoir systems. A combinedcardiotomy and venous blood reservoir is disclosed in U.S. Pat. No.5,411,705 (Thor et al.), hereby incorporated herein by reference. Thistype of reservoir can be adapted and made into a sealed reservoir.

[0017] The Figures illustrate the obturator and its placement in arepresentative duck-bill valve. The obturator was fabricated frompolypropylene and placed in position in a duckbill valve made ofsilicone. FIG. 1 shows obturator 10 comprising cap 20 and plungerelement 30. A perspective view of duck-bill valve 40 is with obturator10 inserted is shown in FIG. 2.

[0018] Valve 40 comprises tips 41 and 43 integrally joined to bodyportion 45 which is itself joined to base 47. Base 47 may also functionas an umbrella valve in response to negative pressure in the reservoir.The plunger element comprises a suitable material. A suitable materialis one that is different from the valve material and one that will notchemically react with or adhere to the material of the valve duringstorage or sterilization procedures. Preferably, the obturator (i.e.,the plunger element and the cap) is molded in a single piece from anysuitable material. Such materials include, but are not limited to,polymeric materials comprising polyolefins, polytetrafluoroethylene(PTFE; also commercially available under the trade designation TEFLON™).

[0019]FIG. 3 shows a cross-sectional view of a combined venous andcardiotomy blood reservoir. This reservoir is sealed, that is, fluidssuch as blood or air do not leak into or out of the reservoir. Similarhard shell reservoirs are disclosed in U.S. Pat. No. 5,411,705 (Thor etal.). This reservoir comprises a rigid housing having a top, a bottom,and a continuous sidewall, where the top and bottom are connected to thesidewall to form an interior chamber. The interior chamber is incommunication with a blood inlet and a blood outlet. A duck-bill valveis also in communication with the interior chamber.

[0020] The interior chamber typically includes a filter unit (not shown)that divides the reservoir into inlet and outlet chambers. Thesechambers are in fluid communication through the filter unit. A means forfiltering and defoaming the blood is disposed within the inlet chamber.In the reservoir shown in FIG. 4, rigid housing 102 has a cover 103, abottom 104, and a continuous sidewall 105 forming enclosed reservoir100. Preferably, housing 102 is made of clear plastic so that medicalpersonnel can observe the blood level in reservoir 100. Sidewall 105 andbottom 104 are integrally formed, molded plastic, and cover 103 is aseparate plastic lid that fits onto top edge 120 and is sealed to it bymeans known in the art, such as by ultrasonic welding or by adhering theparts together with adhesive. Alternatively, cover 103 may be integrallymolded with the sidewall by known methods. Blood flows into reservoir100 through cardiotomy blood or venous blood inlets 111 and 113. Theblood flows through filters to blood outlet 114. Plunger element 30 ofobturator 10 is shown inserted between the tips of duck-bill valve 40which is held in position within portion 50 of cover 103 of thereservoir.

[0021]FIGS. 3 and 4 show the valve and obturator positioned in thereservoir cover. The reservoir is a sealed system, and typically usesvacuum to assist the removal of blood from a patient. Outlet 60 ispositioned at the top of the chamber and is in communication with theoutlet chamber. Duck-bill valve 40 is held in position in outlet 60 byportion 50 of cover 103. Portion 50 is provided with annular projection52. Base or umbrella valve 47 forms a seal with the underside of portion50. Obturator 10 is inserted between the tips of valve 40. Cap 20 ofobturator 10 fits over annular projection 52. If a positive pressurebuilds up in the reservoir, it is released through duck-bill valve 40.If a negative pressure occurs, this can be equalized by the admission ofair through umbrella valve 47.

[0022]FIG. 4 shows a cross-sectional view of valve 40 installed onportion 50 of cover 103 of blood reservoir 100. The valve is incommunication with the outlet chamber of the blood reservoir. Theobturator is removed from the valve during cardiovascular surgery andpermits the flow of air through the valve in the direction of the arrowif there is positive pressure within the reservoir and permits flow ofair to the chamber by means of umbrella valve 47 in the event ofnegative pressure.

[0023] The utility of the obturator was tested by positioning theobturator plunger between the tips of a silicone duck-bill valve fittedin the housing of a blood reservoir, as illustrated in the Figures. Thiswas sterilized under standard EtO (ethylene oxide) conditions. Theobturator was removed. With positive air pressure in the reservoir, thevalve tips separated, thereby preventing a positive pressure in thereservoir.

[0024] In contrast, a reservoir fitted with a silicone duck-bill valvewas treated under the same sterilization conditions as above, butwithout the obturator. The tips of the valve adhered together afterconventional sterilization, allowing pressure to build up within theinterior chamber.

[0025] The obturator is useful when positioned during sterilizationprocedures and during long-term storage of reservoirs fitted with thevalves. The obturator then is removed by the end-user of the bloodreservoir before cardiovascular surgery.

[0026] Although particular embodiments of the invention have beendisclosed herein in detail, this has been done for the purposes ofillustration only, and is not intended to be limiting with respect tothe scope of the appended claims. It is contemplated that varioussubstitutions, alterations, and modifications may be made to theembodiments of the invention described herein without departing from thespirit and scope of the invention as defined by the claims.

What is claimed is:
 1. A method for preventing self-adhesion of the tipsof a duck-bill valve during sterilization comprising: providing anobturator having a plunger element; and inserting the plunger elementbetween the tips of the duck-bill valve prior to sterilization.
 2. Themethod of claim 1 wherein the step of providing an obturator comprisesproviding a plunger element and a cap which is joined to the plungerelement.
 3. A sealed blood reservoir comprising: a top, a bottom, and acontinuous sidewall, the top and bottom connected to the sidewall toform a sealed housing; the sealed housing defining an interior chamber;the housing having a blood inlet and a blood outlet in flowcommunication with the interior chamber; a duck-bill valve having twotips and an integral body in communication with the interior chamber;and an obturator comprising a plunger element positioned between andseparating the tips of the duck-bill valve.
 4. The sealed bloodreservoir of claim 3 wherein the obturator comprises polymeric material.5. The sealed blood reservoir of claim 3 wherein the obturator comprisesa cap integrally joined to the plunger element.
 6. The sealed bloodreservoir of claim 5 wherein the obturator comprises a single piece ofmolded plastic.
 7. A method of preventing pressurization of a sealedblood reservoir, comprising: providing a sealed blood reservoir having atop, a bottom, and a continuous sidewall, the top and bottom connectedto the sidewall to form a sealed housing, the sealed housing defining aninterior chamber, the housing having a blood inlet and a blood outlet inflow communication with the interior chamber, a duck-bill valve havingtwo tips and an integral body in communication with the interiorchamber, and inserting a plunger element between the tips of theduck-bill valve, wherein the plunger element prevents the tips of theduck-bill valve from self-adhering.
 8. The method of claim 7 wherein thestep of inserting the plunger element further comprises providing anobturator comprising the plunger element integrally joined to a cap.